Fellow CSP2 fans I have to share that I can heartily recommend the 6CG7/6FQ7 family of twin triode tube in the center position.I've been running several 6CG7 in the center/input slot, but in particular RCA old equipment pulls, and the result is very nice. It is a tube with a longer plate structure and electrically close to the family of tubes that are spec'd for this preamp. The tube is a bit taller than the height of a 6DJ8/6922. Been running them for 2 months so all is safe. Try it you'll like it

I tried some of those 6CG7's in my MLB headphone amplifier, which is the predecessor to the CSP2. I concluded that they lacked the life, sparkle and verve of a 6N1P-EV or a member of the 6922 family of tubes. So I sold my 6CG's.

This is a brief comparative review of the Lorenz PCC88/E88CC/CCa tubes.I intend to post a more comprehensive review over in the Tubes Asylum Forum in the very near future.The 5 types of Lorenz (Stuttgart Germany) tubes in my possession are

Lorenz 2 Mica Version(a) CCa(b) E88CC(c) PCC88

Lorenz 3 Mica Version(a) E88CC(b) PCC88

I had been using the Lorenz PCC88 2 Mica version rather contentedly for many months now and had only swopped in my other Lorenz tubes from time to time for non-serious comparisons.Recently, I decided to get really serious.For a fair comparison, I managed to burn in all my Lorenz tubes for 100+ hrs.They were all subjected to 24 hours burn in (heater only) and another round of >80 hours of audio burn in using burn-in audio CDs for e.g . the frybaby mp3.

The audio characteristics are as follows:-

Lorenz 2 Mica VersionSince I was in a unique position to be able to compare all these Lorenz variants, one of my discoveries was that the 2 Mica tubes seem to be able to introduce Tube Euphony at certain audio frequencies. They remind me of the frequency equalizers found in some of my older digital hifi equipment.

If you ever played adventure role-playing games such as "The Bard's Tale" series or the recent "Dragon Age: Origins", one of the abilities of a Master Bard is the ability to enthrall audiences. The equivalent over here would be the ability to inject Tube Euphony.

(a) CCa – Best (i.e. most euphoric) Treble or High Frequencies. Best for instrumental audio tracks especially string instruments or Wind instruments.Best resolution and sonic clarity. Best Instrument separation. Backup vocal singers are the most distinct from the lead singers.Mids are slightly warmer than PCC88 version. Soundstage is smaller than PCC88. Mids are slightly more forward than the PCC88.This tube is highly recommended for Classical music with plenty of string instruments. On “The Story” by Brandi Carlile, this tube managed to evoke a strong emotional response in me when the guitar was played. So far, no other tube (Lorenz or otherwise) has ever managed to do so. If you want to add a dose of Tube “magic” to your treble, the Lorenz CCa is highly recommended.

(b) E88CC – Best (i.e. most euphoric) Vocals or Mid Range. Best for music with emphasis on vocals. This tube reminds me of the Telefunken family of tubes which can impart special mid-range magic to any song. 2nd best resolution and sonic clarity. Mids are the warmest in the Lorenz family. Soundstage is smaller than PCC88. Mids are slightly more forward than the PCC88.If you like music with emphasis on vocals, this is the tube for you.If I did not own the 3 Mica Lorenz variants (details below), I would have considered this to be my personal favourite. This tube can make Madonna sing with emotion! Yes, her contemporary pop songs are catchy but this was the first time I felt so moved by her vocals. As for how magical this tube is, let’s just say that I would not hesitate to put out a “Do Not Disturb” sign when I am listening to Ella Fitzgerald with this tube.

(c) PCC88 – Best (i.e. most impactful) Percussive Drums or low end Bass. You can “feel” the greatest impact from this tube. Best 3D effect with the largest soundstage of all 5 Lorenz tube variants. This has a slight sonic “veil” as compared with the other 2 Mica variants.This tube is most recommended for music whereby the bass is emphasised. This tube literally KICKS ASS! When listening to Japanese Taiko drums on my cans, there are times when I feel as though I am listening to real solid vibrationary drums from speakers.

Lorenz 3 Mica Version

(a) E88CC – Balanced Tube with soundstage about the same size as the Lorenz 2 Mica E88CC and CCa. Is the 2nd best in all audio frequencies as compared with the 2 Mica Lorenz tubes. Mids are slightly more forward than the PCC88.

(b) PCC88 - Balanced Tube with the smallest soundstage. Is the 2nd best in all audio frequencies as compared with the 2 Mica Lorenz tubes.

The best way to describe the 3 Mica Lorenz family tube would be “balanced”.

What I mean is that the 3 Mica Lorenz tubes are outstanding on their own with regard to the low end, the mid range and the top end treble frequencies.However, they are 2nd best when compared with the Treble of the 2 Mica CCa, the midrange of the 2 Mica E88CC and the low end bass of the 2 Mica PCC88 which were mentioned above.

Conclusion I would not say that there is any one BEST Lorenz tube.

If your audio chain requires a tweak in the Treble, mid-range or Low End, then I would recommend the Lorenz 2 Mica CCa, E88CC or PCC88 respectively over the other Lorenz tubes.

If you prefer a balanced “workhorse” tube, then the Lorenz 3 Mica tubes are recommended over the 2 Mica variety.

I listen to an eclectic range of music and so my personal favourite tube is now the Lorenz 3 Mica E88CC. This seems to do everything very well. It may lose out to the 2 Mica Lorenz tubes individually but the Lorenz 3 Mica E88CC still manages to impart some (as in a slight amount of) tube euphony into the entire audio spectrum.

As for why I prefer the E88CC over the PCC88, the PCC88 has a slight sonic veil and also has the smallest soundstage of all the 5 tubes which I reviewed. The PCC88 has excellent instrument separation though and when this is combined with a smaller soundstage, the backup singers and main vocals are very distinct but seem to be slightly “squashed together”.

If you are not as perturbed by this audio quirk as I am, then the Lorenz PCC88 3 Mica version should be able to meet the needs of just about any other audiophile out there. Yes, the PCC88 (3 Mica) is really that good!

I am the new owner of a used csp2+. It came with a complement of amperex bugle boy 6dj8/e88cc tubes as well as a mullard cv593 rectifier.

while mids and upper mids sound nice and warm and smooth, the bass is soft and flubby.

where should i begin in tube rolling? it seems the front tube and rectifier have a large effect on tone. i would like to tighten up my bass but not lose the volume and weight of bass. i also prefer a warm sound and deep soundstage. i am VERY sensitive to glare/grain/harshness in the upper mids/lower highs.

I don't know as much about Amperex Bugle Boys as I do other brands, and I'm not really fond of 6DJ8, but what I've read of them and what little experience I have makes me think they would not be presenting "flabby bass." I'd suggest trying 6N1P tubes in the three spots; cryoset.com sells some very nice ones. At least try one in the first position. I find these tubes to give warmth and yet not a hint of flab.

The rectifier may be the culprit. I believe the 2+ comes stock with 5U4G type rectifiers and I'd recommend as old an RCA that you can find. . . Try at least a sixties RCA. With these RCAs I almost always get warm but tight bass.

Just my suggestions! Waiting for my own CSP2+ to arrive in a few months.

Please disregard my message above about soft and flabby bass. I was checking out my system today and realized I had inserted a diy interconnect someone wanted me to try. I swapped it out for my usual cable and everything is now fine. Sorry for the false alarm :-[

where should i begin in tube rolling? it seems the front tube and rectifier have a large effect on tone. i would like to tighten up my bass but not lose the volume and weight of bass. i also prefer a warm sound and deep soundstage. i am VERY sensitive to glare/grain/harshness in the upper mids/lower highs.

Hi setamp, glad to hear that your problem has been fixed.

BTW, for tube rolling, for starters, you can try the solo input tube in front. This has a very significant impact on the rest of the sound from the CSP2+ tube amp.

The (legendary) Joe's tube lore over here is a very good resource for tube rolling tips.